Development of cumulative and availability rate balances in a multi-cylinder turbocharged indirect injection diesel engine

A multi-cylinder turbocharged Diesel engine is analysed from a second law analysis point of view via a single-zone thermodynamic model. For this purpose, a comprehensive digital computer program is developed that incorporates subroutines to simulate, among other things, combustion, heat transfer, indirect fuel injection, mass how through valves, turbocharger and aftercooler behaviour, and real multi-cylinder engine action. This is tested favourably against relevant data from an experimental investigation conducted at the authors' laboratory. A second law analysis is performed in all parts of the engine (cylinder, compressor, turbine, aftercooler, inlet and exhaust manifolds). The analysis describes explicitly all the availability terms existing, i.e. work, heat and mass transfer, availability accumulation in every control volume and fuel flow, thus providing the proper evaluation of every component's irreversibilities, which for the present study are compressor, turbine, inlet, exhaust and combustion. The model is applied to a six-cylinder, turbocharged and aftercooled, indirect injection, four-stroke, medium-high speed diesel engine, installed at the authors' laboratory. Availability rate and cumulative availability terms, with respect to crank angle, for all the processes encountered are presented in diagrams, which show the trends of the availability accumulation and destruction in every component during an engine cycle. Separate diagrams are presented for the main chamber and the prechamber and also for the closed and open parts of the cycle. Tabulation of all second law analysis terms is given for the full load-maximum speed operation and the differences against first law assessments are discussed. Special attention is paid to the correct determination and explanation of the irreversibility quantification and second law efficiencies for every component and for the whole plant. Thus, it is demonstrated that the second law analysis offers a more spherical and comprehensive insight into the processes occurring in a diesel engine than its traditional first law counterpart. Copyright (C) 1996 Elsevier Science Ltd